History of Lexus Hybrid Drive

Lexus Hybrid Drive is now in its fourth generation. Its evolution is the result of genuine and ongoing concern for the harmful effect that vehicle emissions can have on the environment, while simultaneously endeavouring to enhance personal mobility.

Hybrid technology was a strategy initiated in the early Nineties when parent company Toyota began developing an innovative fusion between internal combustion engine, high-voltage battery, and electric motor – all synchronised by cutting-edge software.

More than 20 years later, the term ‘hybrid’ has become synonymous with environmental awareness in transport and is recognised by consumers as one of the most reliable, stress-free drivetrains on the market. But while the core principles of the technology have not changed, there have been numerous refinements along the way. This is our review of the advances Lexus applied with each generation.

Lexus Hybrid Technology: first generation

More to the driver, less from the world

Key models: RX 400h, HS 250h

The Lexus RX holds a special place in our history. Not only did it create the luxury crossover segment on its launch in 1998 but, more importantly, the RX 400h of 2005 (below) was the brand’s first luxury hybrid model.

In this application, Lexus Hybrid Drive was powered by a transversely mounted 3.3-litre 3MZ-FE V6 petrol engine. This was mechanically mated to a P310 hybrid front transaxle (image below) and connected electronically to a Q211 hybrid rear transaxle to provide all-wheel drive capability. The motor generator within this latter unit featured a special planetary gear set that reduced output speed and increased torque.

The nickel-metal hydride (NiMH) battery of the RX 400h consisted of 240 individual cells, having an output of 288 volts. However, a boost function within the inverter assembly increased the voltage up to 650V.
Combining the 211PS output of the petrol engine together with 167PS and 68PS from the front and rear hybrid transaxles respectively delivered a total system output of 272PS. The sensation of plentiful power throughout the rev range was similar to that of a vehicle with a 4.0-litre V8 engine – a feeling that set the tone for a new class of vehicle and provided Lexus with a relatable naming strategy.

Additional information: The Lexus HS 250h (above) of 2009 was our first dedicated hybrid model and the first Lexus hybrid to be equipped with a four-cylinder engine. From the 2.4-litre engine and 204-cell NiMH battery to the P311 hybrid front transaxle, each major component of this first-generation system was smaller and lighter than that found in the RX.

In addition, the HS 250h was the first Lexus to include a selectable EV mode that allowed the vehicle to be driven for short distances on electric power alone.

Lexus Hybrid Drive: second generation

Uninterrupted acceleration

Key models: CT 200h, GS 450h, LS 600h, RX 450h

When it arrived in 2007, the flagship LS 600h saloon (below) was unique in being the only Lexus hybrid model equipped with a powerful V8 petrol engine – in this instance, the 5.0-litre 2UR-FSE. Its combined system output was an impressive 445PS.

Similar to its V6-powered RX 400h and GS 450h siblings, its 240-cell NiMH battery produced 288 volts, with a boost converter capable of increasing this to 650 volts. But its similarities to the GS 450h continued in the engine and hybrid transmission being arranged in a longitudinal, front engine, rear-wheel drive layout.

The L110F hybrid transmission (below) was an upgraded version of the GS 450h E-CVT, which was itself the first of its kind to feature a sequential shift function. Alongside its more powerful generator and electric motor, the L110F included a two-stage motor speed reduction device to increase the functional range of the transmission, simultaneously improving acceleration, high-speed cruising ability and the vehicle’s top speed.

On all-wheel drive models, a mechanical transfer case alongside a limited-slip centre differential was placed after the hybrid transmission to apportion torque between the front and rear wheels.

Lexus LS 600h: low emissions yet high performance

Emitted 75% less CO2 than a city car of 2008

Achieved Super Ultra-Low Emissions Vehicle (SULEV) status

70% cleaner than the average new car in 2008

V8 hybrid delivered smooth overtaking power and acceleration

Rate of acceleration maintained for longer periods

Additional information: Second-generation Lexus hybrid models included manual shift and Artificial Intelligence-Shift (AI-Shift) modes – the first of their kind on a hybrid vehicle. The former enabled the driver to choose when to change gear, providing greater responsiveness in different driving conditions, while the latter made intelligent, automatic gear ratio changes based on road conditions and vehicle attitude (see illustration, above).

Lexus Hybrid Drive: third generation

More efficiency, more response

Key models: ES 300h, IS 300h, NX 300h, GS 300h, GS 450h, RX 450h

The first model equipped with third-generation Lexus Hybrid Drive was the 2012 Lexus ES 300h. However, from a European perspective, the third-generation drivetrain was most popular in the Lexus NX 300h mid-size SUV. It was specifically tuned to offer instant power off-the-line, allied to exceptional combined fuel efficiency.

For this NX 300h application, the 2.5-litre 2AR-FXE four-cylinder Atkinson cycle petrol engine was mated to a P314 hybrid transaxle with a special torque control to reduce pitching motion when used off-road. Meanwhile, at the rear end of all-wheel drive models, the Q211 hybrid transaxle employed in the RX 400h and RX 450h was carried over.

Lexus Hybrid Drive: fourth generation

Powerful visionary

Key models: UX 250h, ES 300h, LS 500h, LC 500h

As revealed in the LC 500h flagship coupe and LS 500h flagship saloon, Multi-Stage Hybrid technology is a key advancement in some models equipped with fourth-generation Lexus Hybrid Drive. The system within the LC310/F transmission comprises a four-stage shift system, which, in tandem with the E-CVT drivetrain it attaches to, replicates the feel of a ten-speed gearbox to significantly improve driver feel and control.

Equally new for Lexus in this generation is the employment of a lithium-ion battery. Offering 252 volts, its energy density is much greater than a NiMH equivalent, which means that a much larger amount of electrical energy can be stored in a smaller space. In fact, the lithium-ion battery in the LC 500h and LS 500h is some 20% smaller and 20kg lighter than the pack used in the LS 600h.

Also smaller and lighter is the petrol engine – a 3.5-litre 8GR-FXS six-cylinder V6. Enhanced with direct injection, intelligent valve control and a host of other improvements, it realises class-leading fuel efficiency and performance.

Additional information: Pairing a potent engine with two powerful electric motors and a self-charging and lightweight lithium-ion battery, the LS 500h is the highest performance LS hybrid in our history. The Multi-Stage Hybrid system multiplies the total system output and torque at the rear wheels through a four-speed transfer case coupled to an electronically controlled power split device.

Additional information: Fourth-generation Lexus Hybrid Drive in the UX 250h includes an efficient new front transaxle. By arranging the power generation and drive motors in a multi-axial layout, the new transaxle is 45mm shorter, while additional measures have been introduced to reduce frictional losses by 25%. The new Power Control Unit is 20% more powerful yet 10% lighter, and a newly developed NiMH battery uses a new electrode material and a more compact cooling to save further space.

Additional information: Public test-drives conducted in February 2019 revealed some interesting statistics about the efficiency of the all new Lexus UX and its fourth-generation Lexus Hybrid Drive technology. Based on a distance of 4,768 miles, the Lexus UX spent 52% of its driving time in EV mode, during which time it accrued 36% of the total mileage. It achieved an average fuel economy figure of 50.5mpg.

Lexus Hybrid Drive: the future

We believe that as the potential of hybrid technology continues to be revealed, the term ‘hybrid’ may take on a new personality. Efficiency will seamlessly merge with performance to unleash the full potential of Lexus engineering.

Comments (6)

Thanks for getting in touch. In terms of architecture and major components, all CT 200h models are equipped with second-generation Lexus Hybrid Drive. However, over the years this system has been improved and refined.

This is an interesting overview. I have a question concerning the ES: given the ease with which a rear electric drive motor can be integrated into the latest hybrid architecture, could Lexus offer an AWD version of the ES300h, for improved traction and poor-weather handling?